The present invention relates to a circuit breaker, and more particularly to a circuit breaker for cutting off an electric circuit in a short time.
In an electric equipment system installed in a vehicle, if any abnormality should occur due to load of power window or the like, or if any abnormality should occur in the wire harness or the like composed of plural wires connecting the battery and each load, a large-current fuse interposed between the battery and the wire harness is melted to cut off between the battery and the wire harness, thereby preventing the loads and wire harness from burning down.
In the electric equipment system using such large-current fuse, however, if any abnormality should occur in the load such as power window, or if abnormality should occur in the wire harness of the like connecting the battery and each load, it is set so as not to melt down unless a current large than the preset allowable value flows in the large-current fuse.
Recently, various protective devices have been developed for cutting off between the battery and wire harness by detecting when a large current close to the allowable value is flowing continuously.